Multiple mercury contact device



Nov. 15, 1938. w. BRTSCH 2,136,874

MULTIPLE MERCURY CONTACI.1 DEVICE Filed July 24, 1937 Mercury/ I `rNVENTO ATTORNEY Patented Nov. 15, 1938 UNITED STATES PATENT oFFicEApplication July 24, 1937, Serial No. 155,488

In Switzerland July 8, 1937 8 Claims.

My invention relates to improvements in multiple mercury contact devicesof the immersion type used in the low tension electrical eld; and theobjects of my improvement are, first, to provide a p ositive and simpleoperative combination of a relatively great number of contacts at theexpense of only little material, small initial cost and small volume;second, to afford facilities Which make thel provision of a vacuum inthe 10 contact cell unnecessary; and, third, to provide means assuringthe positive operation of the contacts in either a horizontal orvertical position.

More particularly, the present invention relates to a mercury contactdevice which is suitable, for example, for operating contacts intelephone work and in other instances where electrical circuits areused.

The present invention makes it possible to control a relatively largenumber of circuits simultaneously, in a simple manner, with decreasedconsumption of material, production costs, and with great economy ofspace.

The mercury contactor devices of the prior art,

and which operate with exclusion of air are operated by tilting anairtight, sealed, mercury con tainer made of glass or other insulatingmaterial. Such arrangements are not suited for the simultaneous controlof a large number of circuits. It

has also been proposed to provide mercury chambers, which are connectedat one side with an electric conductor, with a longitudinally movablecontact plug carried by a resilient link and to have this dip into themass of mercury. It is not possible, however, to operate such contactarrangements constantly under air-tight conditions. becomes oxidized,thus deleteriously affecting the circuit-making capacity and, finally,if this confio dition prevails for a prolonged time, operation of thedevice becomes impossible. A permanently satisfactory circuit closingcan be effected with mercury only if the air is excluded from thecontacting region. This is effected in accordance with the invention byusing two spaced chambers, placed one behind the other and eachcontaining a mass of mercury, and which are connected by a channelthrough which the mercury does not pass. A longitudinally displaceablecontact plug member passes entirely through one of the masses of mercuryand through the channel and is adapted to connect both mercury masseselectrically when extended into contact with the other mass of mercury,and when moved in the opposite direction the contact member moves outWhen electric sparks occur, the mercury (o1. 20o-1s) I attain theseobjects by the device and com.- :l0`

bination of elements shown in two forms of design in the accompanyingdrawing, in which- Fig. 1 is-a vertical section of one form of inventionpossessing two contact cells arranged in line; Fig. 2, a part section ina'largerv scale; and 15 Fig. 3, a control board in elevation incombination with a plurality of contact plunger pins.

The three plates I, 2 and 3 (Fig. l) are made of insulating material andare combined in one block. On the inside faces of the plates l and 3 20and on both sides of the intermediate plate E there is a plurality ofco-axially arranged recesses 4. Appurtenant recesses on the plates i and2, and, respectively,on the plates 2 and 3, together form twocylindrical cells for the recep- 25 tion of mercury which latter in eachinstance constitutes a mercury contact. Between the plates I and 2, or,respectively, 2 and 3 there are at least as many metalliccurrent-conducting layers 5 and 6 or, respectively, 'l and 8 as there 30are cell-pairs arranged in line within the contact block I-3. The saidlayers are insulated from each other by means of the insulating layers9. All these layers are provided with a hole at their junction with theappurtenant contact cell. 35 That conducting-layerwhich is to be incontact With the mercury in a cell-e. g., the layer 6 in Fig. 3-isprovided with a circular hole of a diameter smaller than that of themercury cell 4f. The said latter layer, therefore, with the edge 40 ofits aperture is immersed into the mercury. The contact-,surface betweenthe conducting layer and mercury, therefore, is relatively large so thata positive contact is assured. The aperture Il of those conductinglayers which must 4 not come in contact with the mercury-e. g., theconducting layer 5` in Fig. S-has a greater diameter than the cell 4.'Such a latter layer is not in a current-conducting connection with themercury therefore. The conducting layers are or 5o,

such a small gauge-e. g., 0.004 in.-that the mercury, by virtue of itsinherent cohesion, is not capable of penetrating into the groove l2lying on the periphery of the cell 4. In order,

however, to be absolutely sure that no mercury 55,1

can touch the conducting layer 5, the groove I2 is filled with aninsulating plastic mass such as, e. g., insulating lacquer. Extensionstrips 5 or, respectively, 6 are projected from the correspondingconducting layers beyond the periphery of the plate-aggregate I-3 andeach is provided with one or more connecting wires I3. The said stripsare of unequal length so as to enable one to easily distinguish betweenthe various wires I3. In order to produce a conducting connectionbetween the mercury contents of two coaxial cells lying in line-and thusalso between the conducting layers submerging with the edge of theirapertures into the mercurya capillary bore I4 or, respectively, I5 iscarried from the outside into each cell and also from the one cell tothe adjacent co-axial cell. Thin metal vwires I 6 or, respectively, I6which are fastened to a plate-like carrier I1 or, respectively, I'I'project through the said bores and serve as contact plunger pins. Boththe said pin-carriers I1 and I I are fastened to a common rod I8 ateither side of the block I 3. The said rod I8 is axially displaceablewithin a boss sleeve I9 made of an insulating material and which isholding the plate elements I-3 of the block together. The said rod,furthermore, may be moved forward and backward by any mechanically orelectromagnetically operated mechanism (not shown). The length of thecontact plunger pins I6 and I6 is so dimensioned that its inner end inthe drawn-back or inoperative position is lying in the capillary boreI5, and thus does not touch the mercury in the forward cell; in itsprojected position, however, its tip penetrates into the mercury. In thefirst position the electrical connection between the mercury contents ofadjacent and appurtenant cells I (see top part of Fig. 1) isinterrupted, and in the second position (see bottom of Fig. l) thisconnection is established. With each movement of the rod I8 a connectionis interrupted and another one established in the form of inventionillustrated in Fig. 1. In order that no mercury may pass up to theorifices of the capillary bores I4 and I5 when moving the contactplunger to and fro, i. e., in order to attain a secure sealing betweentwo adjacent appurtenant cells, the ends of the cells are sharplytapered down so that the meniscus of the mercury may project into thisconically tapering space but normally cannot reach up to the orifices ofthe capillary bores, due to the cohesion of the mercury (Fig. 2 atright).

Instead of establishing a contact, when moving the rod I8 in onedirection, in one and the same block and interrupting another contact,the contacts for a plurality of connections may be all established orinterrupted simultaneously and, respectively, may be interrupted orestablished in another block at the same time. A plurality of cell-pairs4 is grouped around the said sleeve (Fig. 4). The plunger-carriers I1and I'I for each cell-pair are provided with very fine Contact pins I6or, respectively, I6. In the direction of a left-to-right motion allplunger-pins I6 establish as many electrical connections between theappurtenant mercury bodies of two cells lying in line, and the pins I6'at the same time interrupt the connections between their appurtenantmercury-bodies. In the case of a greater number of conducting layers andcontact plunger pins the extension strips 22, together with theconnecting wires 23, are of diiferent length and staggered in groupswith relation to each other (Fig. 3), in order to distinguish thedifferent connections and to make the latter easily accessible.

The insulating plate 2 suitably is made of one piece of insulatingmaterial so that the opening spark of a circuit is occupying a verysmall airspace. The latter, on the one hand, is isolated from theoutside by the said insulating material and, on the other hand, by themercury. The oxygen in this airspace very quickly thus is changed tomercury-oxide and a further oxidation afterwards is made impossible.This construction then is avoiding an oxidation of the mercury withoutthe contact-system having to be operated under a vacuum.

Any number of such switching devices, of course, may be combined in anysuitable groupformation into an aggregate, and the plungercarriers maybe operated either over a common drive or, for the purpose of switchingin stages or groups, by a plurality of independent driving devices. Thecontact plunger pins also may be of different, instead of equal, length.

The mercury contact device described may be used in the whole iield oflow tension and, with particular advantage, in telephony and electricsign illumination.

I am aware that prior to my invention mercury contact devices of theimmersion-type have been made in which a metal element is submerged in avertical sense into the mercury. Again, there are such devices which areoperated by tipping, in which the contacts are fused into a glass tubeand flooded with mercury when tipping the tube. I therefore do not claimsuch a rst combination broadly; but what I claim and desire to secure byLetters Patent is:

1. A mercury contact device comprising a block, having at least twospaced, axially aligned, mercury-filled cells therein, and a conductorfor each cell, a movable contact member slidable in said block andpermanently in contact with one of said cells, and selectively incontact with the other cell, the contact member being reciprocable insaid block to make or break a circuit between said cells.

2. A device according to claim 1, in which the block is formed of aplurality of insulating plates and the cells are formed by a series ofco-axial recesses in the abutting faces of said plates.

3. A mercury contact device comprising a sleeve, a plurality ofinsulating plates seated on said sleeve and forming a block, and a shaftreciprocable within the sleeve, said plates having aligned recessesformed in the abutting faces thereof to form spaced cells, mercury ineach cell, and a conductor for each cell, a contact supporting memberseated on one end of said shaft, a contact carried by the supportingmember extending into said block and permanently in contact with onecell and selectively in contact with the next cell, said contact memberbeing reciprocable in said body to make or break a circuit between saidcells.

4. A mer iry contact device comprising a sleeve, a plurality ofinsulating plates seated on said sleeve and forming a block, and a shaftreciprocable within the sleeve, said block having a series orhorizontally and axially spaced, mercury-filled cells and a conductorfor each cell, a contact supporting member seated on each end of theshaft and contacts projecting from said member into the block, andarranged to be in permanent contact with at least one mercuryiilledcell, and selectively in contact with an adjacent axially aligned cell,the arrangement being such that when a contact member on one end of theshaft breaks the circuit between two aligned cells of the series, acontact member on the other end of the shaft will close a circuitbetween two other aligned cells of the series.

5. A mercury contact device comprising a sleeve having a plurality ofinsulating plates seated thereon and forming a block, a shaftreciprocable within said sleeve, said block having at least two spaced,axially aligned, mercuryiilled cells therein, insulated conductinglayers in the block for each cell, 'one conducting layer for each cellhaving an aperture coincident with and of smaller diameter than that ofthe mercuryfilled cell and in contact with the mercury, at least onecontact carrier plate carried by the shaft, at least one contact pinprojecting from said plate and extending into said block, said pin beingpermanently in contact with the mercury of one cell and selectivelyoperable along the axis of said cells to contact the mercury in theadjacent cell to make or break the circuit between said cells.

6. A device according to claim 5, in which the conducting layer not incontact with the mercury has an aperture coincident with and of adiameter larger than that of the cell, and insulating means between theedge of said aperture and the mercury in the cell.

'7l A device according to claim 5, in which the conducting layer not incontact with the mercury is spaced therefrom by a groove of thethickness of the said layer, the thickness of which is such that themercury Will not enter the groove because of the surface tension of themercury, and insulating material in the groove.

8. A mercury contact device according to claim l, in which the block isformed of a plurality of insulating plates combined into at least oneunit and having a bore, a sleeve within the bore to secure said platestogether, a shaft reciprocable in said sleeve and a Contact carrier onsaid shaft, the cells being of cylindrical shape with conically taperingends and horizontally arranged in the block, capillary bores in saidblock extending between the cells and from the cells to the atmosphere,said contact member being carried by said carrier and axiallyreciprocable in said bores, the arrangement of the bores and cells beingsuch that the mercury will not oW from the cells because of its surfacetension and cohion.

WALTER BARTSCI-I.

